Conventionally, as an art for collecting particulate in exhaust gas discharged from an internal combustion engine, an art is known in which an exhaust purification device for an internal combustion engine having a particulate filter in an exhaust route. The particulate filter has honeycomb structure constructed by a porous wall of ceramic or the like, and the exhaust gas is always discharged to the downstream side after passing through the porous wall. An art is well known in which the particulate is burnt and removed which is accumulated in the porous wall when the exhaust gas passes through the porous wall. However, the rotational speed of the internal combustion engine so as to reduce the flow rate of the exhaust gas, and the cooling of the particulate filter by the exhaust gas becomes insufficient. When load on the internal combustion engine is reduced so as to increase residual oxygen amount, excess combustion by the residual oxygen is apt to occur. Therefore, there is a problem in that the possibility of melt damage of the particulate filter is increased.
Then, an art is well known in which the driving state of the internal combustion engine and the temperature of the particulate filter are detected and the reduction of the exhaust flow rate is suppressed so as to prevent the melt damage of the particulate filter. An example of the art is shown in Patent Literature 1.
However, even if the control mentioned above is performed, it is difficult to prevent perfectly the melt damage of the particulate filter. Furthermore, there is a problem in that when the driving of the internal combustion engine is continued while the melt damage of the particulate filter exists, injurious materials such as the particulate included in the exhaust gas are not collected and discharged to the open air.